Sure thing! We've got 138 and we're gonna multiply it by 45. That's the same as adding 138 to itself 45 times.
Step 1: 0 + 138 = 138
Step 2: 138 + 138 = 276
Step 3: 276 + 138 = 414
Step 4: 414 + 138 = 552
Step 5: 552 + 138 = 690
Step 6: 690 + 138 = 828
Step 7: 828 + 138 = 966
Step 8: 966 + 138 = 1104
Step 9: 1104 + 138 = 1242
Step 10: 1242 + 138 = 1380
Step 11: 1380 + 138 = 1518
Step 12: 1518 + 138 = 1656
Step 13: 1656 + 138 = 1794
Step 14: 1794 + 138 = 1932
Step 15: 1932 + 138 = 2070
Step 16: 2070 + 138 = 2208
Step 17: 2208 + 138 = 2346
Step 18: 2346 + 138 = 2484
Step 19: 2484 + 138 = 2622
Step 20: 2622 + 138 = 2760
Step 21: 2760 + 138 = 2898
Step 22: 2898 + 138 = 3036
Step 23: 3036 + 138 = 3174
Step 24: 3174 + 138 = 3312
Step 25: 3312 + 138 = 3450
Step 26: 3450 + 138 = 3588
Step 27: 3588 + 138 = 3726
Step 28: 3726 + 138 = 3864
Step 29: 3864 + 138 = 4002
Step 30: 4002 + 138 = 4140
Step 31: 4140 + 138 = 4278
Step 32: 4278 + 138 = 4416
Step 33: 4416 + 138 = 4554
Step 34: 4554 + 138 = 4692
Step 35: 4692 + 138 = 4830
Step 36: 4830 + 138 = 4968
Step 37: 4968 + 138 = 5106
Step 38: 5106 + 138 = 5244
Step 39: 5244 + 138 = 5382
Step 40: 5382 + 138 = 5520
Step 41: 5520 + 138 = 5658
Step 42: 5658 + 138 = 5796
Step 43: 5796 + 138 = 5934
Step 44: 5934 + 138 = 6072
Step 45: 6072 + 138 = 6210

So, 138*45 = 6210